The loss of functional myocardial cells in ischemic heart disease is a major cause of subsequent morbidity and mortality. Embryonic stem cells (ESC) have been shown to differentiate into cardiac myocytes and represent a promising potential clinical treatment for ischemic cardiomyopathy. The goal of this proposal is to utilize ESC in a murine model of myocardial injury to demonstrate cardiac engraftment and functional improvement. The specific aims that will be addressed are as follows: 1. Direct the differentiation of embryonic stem cells toward a ventricular-specific cardiomyocyte phenotype and assess cell survival and myocardial function following intra-myocardial delivery. 2. Determine both cell and recipient therapeutic interventions that may mitigate antigen independent factors causing early ESC death following transplantation. 3. Evaluate imaging modalities to correlate how cell survival parallels with changes in function.